The present invention relates to an ocular refracting power measuring system, and in particular to an ocular refracting power measuring system, which can measure the astigmatic condition of the eye to be tested at the same time.
As traditional, an ocular refracting power measuring system of so-called photo-refraction type has been known. In the system the retina of the eye to be tested is illuminated by strobe light, the light beam condition on the pupil of the eye to be tested is taken by a camera, and the ocular refracting power of the eye to be tested as measured from these results.
However, in the system of the so-called photo-refraction type, a photograph is taken by an ordinary camera. As the result, the image on the photographed film must be analyzed and ocular refracting power must be calculated from the results of the analysis. Thus, it is not possible to obtain the measurement results with high accuracy. Or, the measurement is made after developing the film, and this means that it is impossible to obtain the measurement results at an instant.
Further, the measurement for astigmatism such as the degree of astigmatism, the angle of astigmatism, etc. has not been taken into account in this conventional type system. Therefore, the measurement for astigmatism must be performed by another measuring system.
By the Japanese Provisional Patent Publication No. 191428/1990, the present applicant proposed an ocular refracting power measuring system, which can measure ocular refracting power with high accuracy and instantaneously according to the distribution of light amount. By this system, the image of light source is projected on retina of the eye to be tested, and the light beam from light source reflected at the retina is blocked by an edge-like light blocking member. The light beam thus blocked is received by a light receiving element, and the ocular refracting power is measured based on the distribution of light amount in the light beam.
The present invention is to offer an ocular refracting power measuring system, which is based on the invention previously applied and which can also measure the degree of astigmatism, the angle of astigmatic axis, etc.